This work proposes topology optimization for steel I-beams, including consideration of bolted beam-column connections with geometric and material nonlinear analysis. The aim is to assess and compare the topological configurations influenced by different connections, examining their stress distribution and rotational stiffness to illustrate the potential of structural optimization. The bi-directional evolutionary structural optimization (BESO) approach is implemented. Furthermore, several bolted steel beam-column configurations were validated based on experimental tests. Subsequently, a series of finite element models were developed, contributing to a comprehensive understanding of the plastic-limit behavior of I-beams under different loading conditions. The proposed method could potentially use a lesser quantity of material while maintaining the same level of structural performance. The results indicate that the implementation of structural topology optimization on I-beams while considering various beam-column connections, yields structural performance similar to that of solid web configurations, achieved through material reduction.

In this paper, a novel optimization technique is implemented to explore the effects of considering uncertain load positions. Therefore, the integration of reliability-based design into structural topology optimization, while considering imperfect geometrically nonlinear analysis, is proposed. By comparing the results obtained from perfect and imperfect geometrically and materially nonlinear analyses, this study examines the impact of nonlinearity on probabilistic and deterministic analyses. Concerning probabilistic analysis, the originality of this research lies in its incorporation of the position of the applied load as a stochastic variable. This distinctive approach complements the consideration of other relevant parameters, including volume fraction, material properties, and geometrical imperfections, with the overarching goal of capturing the variability arising from real-world conditions. For the assessment of uncertainties, normal distribution is assumed for all these parameters. Normal distributions are chosen due to their advantages in terms of simplicity, ease of implementation, and computational efficiency. These characteristics are particularly beneficial when dealing with complex optimization algorithms and extensive analyses, as is the case in our research. The proposed algorithm is validated according to the results of benchmark problems. Structural examples like cantilever beam, pinned-shell, and L-shaped beam problems are further explored within the context of imperfect geometrically nonlinear reliability-based topology optimization, with specific regard to the probabilistic aspect of the location of the externally applied loads. Moreover, the results of the suggested approach suggest that the inclusion of a probabilistic design strategy has influenced topology optimization. The reliability index acts as a controlling constraint for the resulting optimized configurations, including the mean stress values associated with the resulting topologies.

Angled guide plates are used to transmit the forces induced by trains, from the rail seat, to the concrete sleepers. Additionally, the design of the angled guide plates, with an appropriate width, supports tilting protection. Considering the updated requirements of the ML-1 railway line, in the Islamic Republic of Pakistan, an optimization design of the angled guide plate of the Vossloh W14-PK fasteners was carried out herein. The design requirements of the angled guide plate need to meet the requirements of structural stress and protect the plates from deterioration. Given the conducted refined model of the Vossloh W14-PK fastener, it is shown that the force and deformation of the angled guide plate, in the bearing groove adjacent and the outside bolt hole area, are small. Therefore, it was preliminarily recommended that the optimization area of the angled guide plate be divided into the section I, close to the rail groove and section II, outside the bolt hole. The Finite Element Model (FEM) of angled guide plate was established, which is used to analyze the influences of length, width, depth and the number of holes, in section I and section II, on the force distribution, across the angled guide plate. The results show that the scheme of reducing the amount of material and minimizing the influence of force on the structure of the angled guide plate, is to punch three holes in section I and two holes in section II. The holes in section I/II are 20/30 mm in length, 8/8 in width, and 15/8 mm in depth, respectively. The fatigue test showed that the optimized angled guide plate, had good application effects.